1. Field of the Invention
This invention relates to a novel method of encapsulation of weed pathogenic fungi in products having a wheat gluten matrix, the compositions prepared thereby, and their use for the biological control of weeds.
2. Description of the Prior Art
Encapsulation of living biological control agents is a promising means of formulating these organisms into effective products for use against agricultural pests. Biological control using living natural enemies of pests is distinguished from control by the use of chemical pesticides. When encapsulated or entrapped in a solid matrix, delicate biological control organisms (agents) are sheltered from rapid desiccation, microbial competition, and other adverse environmental factors which can limit their practical utility.
Encapsulation techniques for incorporating biological control fungi in an alginate matrix have been widely used. In U.S. Pat. No. 4,718,935, Walker et al. disclose the encapsulation of fungi in alginate gel pellets for the control of weeds. In U.S. Pat. No. 4,724,147, Marois et al. disclose the encapsulation of fungi in alginate pellets for control of soilborne plant diseases. In U.S. Pat. No. 4,668,512, Lewis et al. disclose the preparation of alginate pellets that contain wheat bran as nutrient for encapsulated fungi, said pellets used for the control of soilborne plant pathogens. In each of the alginate-based methods referenced above, a fungus was added to a sodium alginate solution that also contained fillers/adjuvants, and the mixture was added dropwise into a CaCl.sub.2 solution which reacts with the alginate to transform the droplets into alginate gel pellets containing the fungus. None of the referenced alginate-based patents teach the use of a wheat gluten matrix to encapsulate weed pathogenic fungi.
Biocontrol agents have also been incorporated into a starch matrix. In U.S. Pat. No. 4,859,377, Shasha et al. disclose the encapsulation of entomopathogenic biocontrol agents by blending the agents into an aqueous dispersion of amylose-containing, pregelatinized starch in which reassociation of amylose molecules occurs upon dispersion in an aqueous system causing an insolubilization of the starch matrix. Shasha et al. do not teach the use of a wheat gluten matrix to encapsulate weed pathogenic fungi.
Wheat flour has been used as a nutrient in formulations that contain fungi, but not as a source of gluten to provide cohesiveness and a matrix structure for encapsulation of weed pathogenic fungi. In EP 226394, McCabe et al. disclose the production of microbial inoculants for agricultural uses. Wheat flour is disclosed as a preferred nutrient for fungal cultures, but not as a source of gluten to encapsulate weed pathogenic fungi.